Cell-free mitochondrial DNA in CSF is associated with early viral rebound, inflammation, and severity of neurocognitive deficits in HIV infection

Abstract

Cell-free mitochondiral DNA (mtDNA) is an immunogenic molecule associated with many inflammatory conditions. We evaluated the relationship between cell-free mtDNA in cerebrospinal fluid (CSF) and neurocognitive performance and inflammation during HIV infection. In a cross-sectional analysis, we evaluated the association of mtDNA levels with clinical assessments, inflammatory markers, and neurocognitive performance in 28 HIV-infected individuals. In CSF, we measured mtDNA levels by droplet digital PCR, and soluble CD14 and CD163, neurofilament light, and neopterin by ELISA. In blood and CSF, we measured soluble IP-10, MCP-1, TNF-α, and IL-6 by ELISA, and intracellular expression of IL-2, IFN-γ, and TNF-α in CD4+ and CD8+ T cells by flow cytometry. We also evaluated the relationship between CSF pleocytosis and mtDNA longitudinally in another set of five individuals participating in an antiretroviral treatment (ART) interruption study. Cell-free CSF mtDNA levels strongly correlated with neurocognitive performance among individuals with neurocognitive impairment (NCI) (r=0.77, p=0.001). CSF mtDNA also correlated with levels of IP-10 in CSF (r=0.70, p=0.007) and MCP-1 in blood plasma (r=0.66, p=0.01) in individuals with NCI. There were no significant associations between inflammatory markers and mtDNA in subjects without NCI, and levels of mtDNA did not differ between subjects with and without NCI. MtDNA levels preceded pleocytosis and HIV RNA following ART interruption. Cell-free mtDNA in CSF was strongly associated with the severity of neurocognitive dysfunction and inflammation only in individuals with NCI. Our findings suggest that within a subset of subjects cell-free CSF mtDNA is associated with inflammation and degree of NCI.

Mitochondrial injury and cognitive function in HIV infection and methamphetamine use

“…An individual with a GDS score of greater than 0.5 was deemed to have neurocognitive impairment [22]. In this study, we analyzed GDS as a continuous variable to measure neuropsychological performance.…”

“…We quantified levels of mtDNA per cell by measuring the copy numbers of the mitochondrial NADH dehydrogenase 2 (MT-ND2) (Applied Biosystems, Waltham, MA) using a standard Applied Biosystems assay (Cat. # 4331182), and the cellular control gene ribonuclease P protein subunit p30 (RPP30) (Integrated DNA Technologies, Coralville, IA) which is present in two copies per cell as described in our previous study [22]. The names and sequences of these primer-probe sets are as follows: RPP30-F (5′-GATTTGGACCTGCGAGCG-3′), RPP30-R (5′-GCGGCTGTCTCCACAAGT-3′), and RPP30-P (5′-HEX/CTGACCTGA/ZEN/AGGCTCT/IBFQ-3′).…”

“…We also investigated the magnitude of mitochondrial genetic defects in relation to neurocognition. Given our previous work demonstrating the correlation between cell-free CSF mtDNA levels and neurocognitive performance [22], we also investigated cell-free CSF mtDNA in these groups. Elucidation of the relationship between METH use and HIV infection on mtDNA may help improve our understanding of the role of mitochondrial injury in HIV-associated neurocognitive disorders.…”

Increased cell-free mitochondrial DNA is a marker of ongoing inflammation and better neurocognitive function in virologically suppressed HIV-infected individuals

“…Recently, we described associations between higher levels of mtDNA in CSF and increased markers of inflammation and neurocognitive deficits in a cohort of 31 HIV-infected individuals [10]. This previous cohort was limited by variable uptake of antiretroviral therapy (ART) and most individuals were not virally suppressed in their blood plasma and CSF at the time of sampling [10].…”

“…This previous cohort was limited by variable uptake of antiretroviral therapy (ART) and most individuals were not virally suppressed in their blood plasma and CSF at the time of sampling [10]. The ongoing viral replication may have confounded our ability to use mtDNA as a marker of neurodegeneration.…”